feat: modernize address list with drag-transfer, labels, and UX polish

- Rewrite RenderSharedAddressList with two-pass layout architecture
- Add drag-to-transfer: drag address onto another to open transfer dialog
- Add AddressLabelDialog with custom label text and 20-icon picker
- Add AddressTransferDialog with amount input, fee, and balance preview
- Add AddressMeta persistence (label, icon, sortOrder) in settings.json
- Gold favorite border inset 2dp from container edge
- Show hide button on all addresses, not just zero-balance
- Smaller star/hide buttons to clear favorite border
- Semi-transparent dragged row with context-aware tooltip
- Copy-to-clipboard deferred to mouse-up (no copy on drag)
- Themed colors via resolveColor() with CSS variable fallbacks
- Keyboard nav (Up/Down/J/K, Enter to copy, F2 to edit label)
- Add i18n keys for all new UI strings

src/app.h

@@ -202,6 +202,16 @@ public:
     void unfavoriteAddress(const std::string& addr);
     bool isAddressFavorite(const std::string& addr) const;
 
+    // Address metadata (labels, icons, custom ordering)
+    void setAddressLabel(const std::string& addr, const std::string& label);
+    void setAddressIcon(const std::string& addr, const std::string& icon);
+    std::string getAddressLabel(const std::string& addr) const;
+    std::string getAddressIcon(const std::string& addr) const;
+    int getAddressSortOrder(const std::string& addr) const;
+    void setAddressSortOrder(const std::string& addr, int order);
+    int getNextSortOrder() const;
+    void swapAddressOrder(const std::string& a, const std::string& b);
+
     // Key export/import
     void exportPrivateKey(const std::string& address, std::function<void(const std::string&)> callback);
     void exportAllKeys(std::function<void(const std::string&)> callback);